Express on Bun is a Vercel boilerplate that pairs the Express.js web framework with the fast Bun JavaScript runtime, giving you a ready-to-deploy backend template for Vercel's serverless platform.
What is the Express on Bun template?
Express on Bun is a starter project from Vercel's official examples repository that combines the Express.js routing layer with the Bun runtime. It takes a minimal Express application as its input and produces a deployable serverless backend on Vercel, with a live reference available at example-express-bun.vercel.app. Users run the project locally with bun install and vc dev, then deploy it using vc deploy from the Vercel CLI.
Key Features
- Bun runtime — Runs the Express server on Bun instead of Node.js, tapping Bun's built-in bundler and package manager.
- Express framework — Includes a basic Express app with standard HTTP routing so you can add endpoints immediately.
- One-click deployment — The "Deploy with Vercel" button clones the repository and kicks off a new deployment without leaving the browser.
- Vercel CLI workflow — Local development uses
vc dev, production builds usevc build, and publishing usesvc deploy. - Live example — The template ships with a working live deployment at example-express-bun.vercel.app for reference.
- Official starter — Maintained by Vercel as part of the framework-boilerplates collection on GitHub, ensuring it stays aligned with current Vercel tooling.
Who should use Express on Bun?
- Backend developer who wants to test Bun's runtime behavior while keeping Express's familiar request handling.
- Prototype engineers who need a minimal, deployable backend in minutes and prefer Vercel's CLI to manage staging and production.
- Team evaluating Bun on serverless infrastructure can use this exact template as a baseline for benchmarks.
Use cases
- REST API launch: Create a new backend by cloning this template, then add Express routes to serve JSON data or proxy third-party APIs.
- Serverless experimentation: Use the pre-built Vercel configuration to see how Bun executes simple HTTP handlers in a serverless environment.
- Deployment practice: Learn the Vercel CLI flow (dev, build, deploy) by working with a small, self-contained Express app.
How does the Express on Bun template work?
After cloning the repository, you install dependencies with bun install and start a local development server with vc dev, which listens on http://localhost:3000. To create a production bundle, run vc build, and to push it live, run vc deploy while logged into Vercel. The template includes the necessary Vercel configuration to run Bun as the runtime.
FAQ
What runtime does this template use?
It uses Bun, a modern JavaScript runtime that is also a bundler and package manager. The Express code runs on Bun's runtime rather than Node.js.
What are the prerequisites to run it?
You need the Vercel CLI installed globally on your machine. The template's setup steps assume you have Bun available, since it uses bun install for dependency management.
Can I deploy without the Vercel CLI?
Yes. The Vercel Deploy button lets you create a new deployment directly from the repository URL by clicking it in the README. It clones the code into your Vercel account and builds it automatically.
Where is the live example?
The README links to a running instance at example-express-bun.vercel.app, which reflects the default Express app created by this template.
